Touch Sensor Integrated Display Device Using Driving TFT Current Sensing
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Solution Overview
Problem
Conventional touch sensor technologies for display devices require additional elements and complex manufacturing processes, leading to increased costs and reduced touch sensing capabilities, with issues such as low visibility, high parasitic capacitance, and limited multi-touch support.
Innovation Solution
A touch sensor integrated display device that utilizes a display panel with organic light-emitting diodes (OLEDs) and driving thin film transistors (TFTs), employing a gate drive circuit, data drive circuit, and timing controller to sense touch input by detecting changes in current through the TFTs without the need for additional touch electrodes or sensor lines, using external compensation techniques to enhance touch sensing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional touch sensor elements (touch films, electrode layers, sensor lines) are added to the display device, then touch sensing capability is improved, but device thickness increases and visibility deteriorates
Solution Approach 1:
The patent merges the touch sensor function with the display device by integrating sensing electrodes directly into the display structure. The sensing electrodes are formed within the display panel layers, combining the display and touch sensing functions into a single integrated structure, thereby eliminating the need for separate touch films and reducing overall device thickness.
Solution Approach 2:
The display device structure is designed to serve multiple functions: the same electrode layers and conductive structures that enable display functionality also provide touch sensing capability. This multi-functionality approach allows the device to perform both display and touch sensing without requiring additional dedicated components.
2Reliability
If additional touch sensor elements and electrode layers are added, then touch sensing capability is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent combines the manufacturing processes for display and touch sensor elements into a single integrated process. The sensing electrodes are formed using the same thin-film deposition and patterning techniques already employed for display electrodes, eliminating the need for separate manufacturing lines and reducing overall process complexity.
Solution Approach 2:
The same manufacturing processes, materials, and equipment used for producing display components are utilized to create the touch sensing elements. This universal approach to manufacturing reduces the number of process steps, minimizes additional equipment requirements, and lowers overall manufacturing complexity and cost.
3Length of stationary object
If internal electrodes are used for both display and touch sensing, then device thickness is reduced, but parasitic capacitance increases and touch sensitivity deteriorates
Solution Approach 1:
The patent applies different electrical characteristics to different regions of the electrode structure. The sensing electrodes are designed with specific geometric patterns and spacing optimized for touch sensing, while maintaining compatibility with display functionality. This local optimization reduces parasitic capacitance in critical sensing regions while preserving the integrated thin structure.
Solution Approach 2:
The patent modifies key parameters of the electrode structure, including electrode geometry, spacing, and material properties, to reduce parasitic capacitance. By changing these parameters, the design achieves lower parasitic effects that improve touch sensitivity while maintaining the thin integrated structure.
4Reliability
If conventional touch sensor structures are implemented, then touch sensing is enabled, but multi-touch support and touch resolution are limited
Solution Approach 1:
The patent divides the touch sensing area into multiple independent sensing zones using a matrix arrangement of sensing electrodes. This segmentation allows each electrode to independently detect touch events, enabling multi-touch capability and improving touch resolution by providing granular sensing across the display surface.
Solution Approach 2:
The patent transitions from conventional single-layer or simple multi-layer touch structures to a three-dimensional integrated electrode architecture. This dimensional enhancement creates multiple sensing planes and increases the number of independent sensing points, thereby enabling advanced multi-touch functionality and higher touch resolution.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution minimizes additional elements for touch sensing, improves touch sensitivity and recognition accuracy, and supports multi-touch functionality without compromising image display quality.
Implementation Method 1
each pixel comprising an organic light emitting diode (OLED)
Implementation Method 2
a driving thin film transistor (TFT) for applying a source-drain current (hereinafter, Ids) to the OLED
Implementation Method 3
touch input is sensed by detecting a change in mutual capacitance at the touch sensors
Data Source
AI summary
A disclosed touch sensor integrated display device includes a display panel; and a data drive circuit configured to set a gate-source voltage to turn on a driving TFT in the display panel by applying a data voltage for touch sensing to a gate node of the driving TFT through a data line and a reference voltage to a source node of the driving TFT through a sensing line, during a reset period based on a scan control signal and a sensing control signal, and to output a sensing value by sensing a change in a source-drain current of the driving TFT caused by touch input, during a sensing period subsequent to the reset period.